Creating 3D pixel modeling?
If it is a 3D model of a sprite you want, then I have actually made a Python Script / Addon that takes an image and converts each pixel to a cube with a material of the same color.  

https://gist.github.com/MrSprite/ff7fda1ec4bf6850d357.  Go here and click the button that says Raw. Then you can right click on the page that opens to download the .py file.

Install it in Blender like a normal addon.

I don't recommend using images over 100x100 unless you want Blender to lag a lot.  Also it takes around 1 minute to generate 100x100 cubes, but only .39 seconds to do a 32x32 image.

Also, if a pixel has ANY transparency it will not be created, so be careful!